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C. P. Hernandez-Luna, R. Babu, G. Strong, E. L. Irving; New Attended Field of View (AFOV) test. Invest. Ophthalmol. Vis. Sci. 2009;50(13):4728.
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An important challenge for eye care practitioners is meeting the needs of an ever-increasing elderly population. Many standard vision tests are inadequate for determining true performance in real life situations. One test that was developed to address this issue is the Attended Field of View (AFOV) test (Coeckelberg et al, 2004), which was designed to estimate the functional field of view when people are allowed to make habitual head and eye movements. The original AFOV test is no longer available. This research seeks to develop a replacement AFOV test and to demonstrate its reliability as an assessment tool.
Seven participants (mean age 29.3 years) were evaluated on three separate occasions. All subjects had visual acuities equal or better than 20/25 and no history of visual field loss. A computer-generated display was observed from a 60cm distance. It consisted of 24 white circles on a gray background and one open circle (target). The circles were organized with one circle in the centre and eight located radially at three eccentricities (4, 8, and 12 degrees). Participants were required to locate the target circle and to identify the gap direction. A response was considered correct when both the location and gap direction were accurate. Forty trials were randomly presented at each location. Using a weighted staircase method based on presentation time each location was evaluated independently. The data was analyzed using repeated measures ANOVA.
There was no significant interaction between visits and locations (p=0.710). Performance between visits 2 and 3 was not significantly different (p=1.000), but both were significantly different from performance on visit 1 (p=0.004, p = 0.002). This was interpreted to be due to a learning effect. A main effect of eccentricity (p=0.000) and an effect of direction (p=0.000) were also found. The locations in the vertical axis presented less sensitivity than locations in the horizontal axis.
The use of the new AFOV test requires a practice time before its use in order to avoid the confounds of a learning effect, but subsequent data is repeatable in young people. When interpreting the results of this test one must account for both eccentricity and direction.
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